Air-spring device



Sept. 14, 1926.

J. J. MCELROY AIR SPRING DEVICE Filed April 14, 1924 NVENgR .dc

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Patented Sept. 14, 1926.

JOHN if. MCELROY, 0F NEW -IIAVEN, CONNECTICUT; ASSIGNOR TO TI-IE WESTING- HOUSE AIR SPRING COMPANY, OF NEW HAVEN, CONNECTICUT, .A CORPORATION OlE" PENNSYLVANIA.

AIR-SPRING DEVICE.

Application filed April 14,

yMy present invention relates to pneumatic cushions and particularly to air springs such as are used on vehicles to absorb shocks imparted from the roadway to the running lt relates more particularly to such a device in which a piston and cylinder which comprises the main parts thereof are oil sealed and, in which the said piston acting` within a certain portion of said cylinder serve as their own pump to automatically return such oil as leaks from the main cushion chamber back thereto.

In the device of my invention I provide a cylinder closed at the top and bottom with a piston therein connected to a rod passing through said bottom of the cylinder. This piston divides the cylinder' into a main cushion chamber at the top in which is placed a quantity of oil for sealing the space between the contiguous surfaces of said piston and cylinder and air under pressure, and into a rebound and oil collecting` chamber at the bottom. The lower part of the piston is shaped to contact substantially throughout the surface of any oil. which collects in said bottom chamber except where grooves cut in the cylindrical surface of said piston parallel withits axis connect withsaid lower chamber whereby when said pistou. exerts pressure on said collected oil it will be forced upwardly through said grooves past cup washers carried by said piston and back into said cushion chamber. From same purpose I cutsaid oil return grooves in the cylinder wall from the desired distance.

lt is therefore the purpose of Ymy invention to provide a pneumatic cushioircompris ing` a cylinder closed at the top and bottom with a piston therein and a piston rod passing through the bottom. said piston beina` provided with cup washers tending to hold oil placed in the upper chamber formed by said piston and cylinder so as to function on the down stroke as a pump to automa-tically return any oil which may have leaked from said cushion chamber past said cut washers.

lt is further a purpose of my invention to 1824. Serial No. 706,299f

have said piston and cylinder formed at their bottoms to function as a rcboundcushion chamber which acts to soften any vio-- lent reaction set up through the functioning of said main cushion chamber.

ln the dre-wing which forms part of this appli cation 4 l is a ver al inidcection looking in the direction of the `arrows on line om?) of an air spring' comprising a cylinder and piston which form a main compression chamber above the piston and a rebound chamber and return oil pump chamber below said piston. Fig'. 2 is a section along line a-a showing' the relative areas of the part of the piston which acts to pump bach stray oil and of the channels through which such oil is returned. v y

In the drawing' the cylinder l is closed at its top by the dome 2 which is threaded to it. The opening 3 in said dome is closed by the air valvel. The cap 5 screwed to 70 said dome about the valve serves to protect the valve. The bottom of said cylinder l screws into the cup shaped bottom 6 through the center of which extends the` piston rod 7. The bushing 8 seated inthe central hole of 75 said bottom 6 extends about said rod 6 to a considerabledistance above the inner sur` face of said bottom. On a shoulder formed onr said piston rod 7 lits the piston skirt 9 which depends downwardly about and spaced from said piston rod to form a chain beV l() of ccmsiderable volume therein. At about the .midpoint of the stroke4 limits of the rod 7, the lower edge of said skirt 9 conta cts with the downwardly turned cup wash- S5 er ll mounted on the upper end of said bushing; S by the ring` l2 and screws 13, whereby the boundary of said chamber l0, which is the recoil or rebound compression chamber, is completed. The inner .vertical 9.0 surface ofthe inner side of said skirt 9 is formed to make a sliding fit with the outside of said bushing;` 8 which is chambered at its upper outside edge to allow movement of said washer 1l when said skirt 9 moves 95 past it. The outer surface of said skirt 9 makes a sliding tit with the inside surface ot the cylinder 1. The grooves 1/1 extend along the outside surtace of the skirt 9 throughout the length thereof and are in total cross-sectional area small in proportion to the area of the lower annular end ot said skirt. An upwardly turned cup washer 15 is held on the top of said skirt 9 by the ring 16 and bears against the sides of the cylinder. VEhe cylindrical ring 17 serves to space said skirt 9 from the piston 'follower 18 which rests on it and has 'termed in its lower surface an annular channel 19 of an inner diameter the same as that ot said ring 17 whereby said ring 17 is positioned axially concentric in the said piston rod 7; The nut 32 threaded Vonto the end ot the piston rod 7 serves to Vcylindrical piston head 23, which in turn is held firmly in place by the nut 241 threaded onto the end ot the piston rod and bearing on the itat washer 25 which in turn bears on a Spacing channel in the top ot said head VT. Said head 23 tor the greater portion ot its length tits closely about the outside ot tollower 18, but at its upper end t'orms a bearing surface which makes a sliding fit with the inside ot said cylinder 1. The upper or Compression chamber 26 is provided with a quantity of oil 27 which serves to seal the contacting surfaces ot the various parts oit the piston and the cup washers.V In the drawing there is shown as having leaked from the compression chamber the body of Voil 27 in collecting chamber 28.

i means of suitable fittings not shown which connect respectively with the lower end 31 or the piston rod and .said bottom cup 11.

In the use and operation ot my device, chamber 26 is -supplied with a quantity ot oil 'lor sealing the joint between the piston and the cylinder and air is pumped unde pressure into said chamber 26 through said check valve 1. The cylinder in some Suit able manner as through connection with cup 6 is mounted to the trame ot an automobile, tor instance, and the piston through the lower endl of the piston rod 7 is connected to the running gear thereof. Then any great bump or shock transmitted to said piston rod 7 'from the roadway by way oit the running` gear is further transmitted through the piston to the air in the compression chamber 26 which air by further conipression as a result oi' said shock absorbs the shock and dissipates it thus preventing its transmission to the vehicle body.

1n the movement of the piston in the cylinder a little oil usually escapes past the cup washers 15 and 21 and collects in said chamber 28. The bottom oi skirt 9, however, has an area substantially that of the surface of the oil in said chamber 28, except for the channels 141, sothat when a shock exerting torce is relieved from chamber 26 and a consequent rebound occurs the skirt 9 moves into said chamber 28 and against the surface ot oil 27 collected therein with considerable torce with th-e consequence that said oil 27 or a part ot it is torced upwardly through said channels 14 and past the cups 15 and 21 back into said chamber 26. W hen there is no oil in said chamber 28 or alter it has been forced out, said bushing 8, operating as a piston in said chamber 10, serves to take and absorb the shock of the rebound.

1.v 1n an air spring, in combination, a substantially vertical cylinder closed at both ends, a piston in said cylinder connected to a piston rod passing through the bottom ot said cylinder, oil and air above said piston under pressure, and means comprising a skirt on said piston for pumping back any oil which leaks trom above said piston and collects below it, said skirt having a sliding' lit with said cylinder and longitudinal grooves in the side ol' said skirt.

2. In an air sprinO', in combination, a substantially vertical cylinder closed at both ends, a piston in said cylinder dividing it into an upper compression chamber and a lowerchamber, a piston rod connected to said piston and passing through the lower end thereof, oil and air under pressure in said upper chamber, uupwardly extending cup washers about said piston and contacting with said cylinder, an annular skirt` on said piston having a. sliding tit with said cylinder and extending downwardly from the lowermost ot said cupwashers and grooves trom said washer to its lower edge, and a bushing about said piston rod cooperating with the said skirt to ite-rm a pump operable to return leaked and collected oil from the bottom ot said lower chamber back past said cupwashers and to form with the. interior ot said piston a rebound compressi on chamber.

8. 1n an air spring, a substantially vertical cylinder closed at its top and bottom, a piston therein dividing` said cylinder into an upper and a lower chamber, a piston rod connected to said piston and passing through the lottoin of said cylinder, an annular skirt on said piston extending downwardly and `making a sliding tit with said cylinder,

and a bushing about said piston rod eXtending upwardly, oil and air under compression ing' upwardly from the bottom of the cylnin said upper chamber, and upwa'dly eX- l0 der and making a sliding fit on its outside tending annular cup washers between said with the inside of said skirt, said skirt piston and seid cylinder.

and bushing,- serving when in registry to In testimony whereof l hereto aflx my divide. from said lower chamber .an enclosed signature.

collecting and pumping chamber, channels in the annular surface of said skirt eXtend- JOHN J. MCELROY. 

